<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <button>按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>
    <button>按钮5</button> //这是一句注释
</body>

<script>
    let buttons = document.querySelectorAll('button');
    console.log(buttons);
    for (let i = 0; i < buttons.length; i++) {
        buttons[i].onclick = function() {
            for (let j = 0; j < buttons.length; j++) {
                buttons[j].style.backgroundColor = '';
            }
            this.style.backgroundColor = 'pink';
        }
    }
</script>

</html>